Add image preview microservice

Author: julianduque

image-preview.js

@@ -0,0 +1,48 @@
+'use strict'
+
+const fs = require('fs')
+const path = require('path')
+const mime = require('mime-types')
+const { send, json } = require('micro')
+const Filter = require('instagram_js_filter')
+const effects = new Filter()
+
+//
+// This microservice will be served as /preview
+//
+// It will receive the name of the uploaded image and the filter in a JSON
+// {
+//   "name": "xxxx-xxx-xxx-xx.jpg",
+//   "filter": "sepia"
+// }
+//
+module.exports = async function (req, res) {
+  const body = await json(req)
+  const { name, filter } = body
+
+  const type = mime.lookup(name)
+
+  let preview
+  try {
+    preview = await convert(name, filter)
+  } catch (e) {
+    send(res, 500, e.message)
+  }
+
+  const imagePreview = `data:${type};base64,${preview.toString('base64')}`
+  send(res, 200, { image: imagePreview })
+}
+
+//
+// Convert an image and applies a filter
+//
+function convert (src, filter) {
+  return new Promise((resolve, reject) => {
+    fs.readFile(path.join(__dirname, 'uploads', src), (err, buffer) => {
+      if (err) return reject(err)
+
+      const result = effects.apply(buffer, filter, {})
+      resolve(result)
+    })
+  })
+}